This invention relates generally to the field of vehicle seat assemblies and more particularly to a method of forming a vehicle seat having a stylized, contoured surface.
Typically, in the production of a vehicle seat trim cover, a forming tool is constructed and used which has a surface contour complementary to the final desired shape of the vehicle seat or back. One example of such a tool is disclosed in U.S. Pat. No. 4,740,260, issued Apr. 26, 1988, entitled "Method And Apparatus For Manufacturing Seats And Articles Formed Thereby", assigned to the assignee of the present invention. Another method of forming contours in vehicle seat members is disclosed in U.S. Pat. No. 4,860,415, issued Aug. 29, 1989, entitled "Vehicle Seat Assembly With Pour In Place Foam Body", and assigned to the assignee of this application.
In both patents, the vehicle seat cover member is placed inside out on a forming tool having the desired complementary contours to the finished product. Pressure is applied against the cover member to shape the cover member to the contours of the forming tool. The forming tools described in the patents must be individually made with the desired surface contours. Conventionally, a new tool or mold half is required if a new design contour is called for. Accordingly, the tools are relatively expensive to produce.
Forming tools and mold halves having removable inserts which permit simple modification of the insert instead of replacement of the entire tool are described in copending application Ser. No. 310,351, filed 2-14-89, also assigned to the assignee of this application. These forming tools having removable inserts allow quick interchange of styles for producing vehicle seat covers having differing contours as consumer demand dictates and may be used with the present invention.
During assembly of the vehicle seat, the style insert material is placed onto the forming tool and drawn down into conformity with the contours of the forming tool insert by either vacuum forming or the application of a complementarily shaped forming tool. A foam bun is then applied to the seat cover and adhered thereto with a suitable adhesive.
The foam bun, however, must have the predetermined shape corresponding to the inserts used to form the contours in the seat cover in order to properly form the desired contours. Thus, different foam buns are required for each different styling contour desired in a finished vehicle seat surface.
The present invention eliminates the requirement for foam buns having a predetermined finished shape and simplifies the selection of style inserts to more economically form the finished vehicle seat or vehicle seat back assembly. The method according to the present invention forms a composite insert by first laminating a porous cloth fabric or similar economical trim material to a polymeric foam sheet to form a flexible composite. This composite is then cut into the appropriate shape of the finished insert. The vehicle seat or back skirt fabric is then sewn to the edges of the cloth fabric of the insert. The composite portion is then positioned onto a forming tool with the cloth surface of the composite against the forming tool style insert.
An impermeable barrier sheet, such as a polyolefin film is placed over the foam surface of the composite and the composite is then pressed into conformity with the style insert by vacuum drawing the composite into conformity with the style lines. A generic foam bun having a flat surface is sprayed with a suitable adhesive, such as polyurethane glue and pressed against the drawn composite. Heat in the form of steam or the like is then forced through the composite to at least partially evaporate the barrier sheet and thus provide for bonding of the foam of the composite to the foam bun. In the alternative, the barrier sheet can be incorporated in the composite at a position between the fabric and foam sheets.
Thus, as just described, a generic foam bun may be utilized to form a vehicle seat or back cushion having stylized contours without the necessity for specially shaped molds.
During the vacuum drawing of the composite, the barrier sheet of polyolefin film placed over the composite forms a barrier layer which makes the composite impermeable and allows atmospheric pressure to press against and compress the foam and fabric into conformity with the forming tool surface. The completed assembly is then removed and the skirt of the vehicle seat or back is secured to the underside of the assembly to complete the cushion construction.
Thus, the method for forming a portion of a vehicle seat assembly according to the present invention includes the steps of:
a. laminating a sheet of breathable cloth fabric trim material to a sheet of flexible thermoplastic foam to form a composite; PA1 b. placing the composite on a forming tool having an upper surface shaped to the predetermined surface contour; PA1 c. combining a barrier sheet with the composite on the forming tool; PA1 d. applying a vacuum between the tool and the composite to draw the composite against the upper surface of the insert; PA1 e. applying an adhesive to one surface of a foam bun; PA1 f. pressing the surface of the bun against the composite on the forming tool; and PA1 g. heating the composite and the barrier sheet to at least partially evaporate the barrier sheet, thus forming the portion of the vehicle seat having the desired styled surface contour.
Once the foam bun is bonded to the composite by the application of heat and pressure, the cover with foam bun attached is removed from the forming tool and the skirt of the seat or back cover is wrapped over the body of the foam bun to at least partially enclose the bun.
Further objects, features and advantages of the present invention will become evident from a consideration of the detailed description when taken in conjunction with the accompanying drawing and the appended claims.